The invention relates to a transmitting and receiving module, i.e. a transceiver module, for bidirectional optical message and signal transmission. The module includes at least one optical transmitter, at least one optical receiver, a fiber connection opening for an optical fiber, lens coupling optics, and at least one beam splitter arranged in the free beam path. In particular, the invention relates to a transmitting and receiving module which is produced in accordance with leadframe technology and can therefore be fabricated in a suitable way for surface mounting.
In fiber-optic message transmission, for some years the prior art has been, in the full-duplex or half-duplex method, to transmit at least one channel bidirectionally in each case.
For example, European patent application EP-0 463 214 describes a transmitting and receiving module, known as a BIDI module, for bidirectional optical message and signal transmission. In the case of that module, the two active components (optical transmitter and optical receiver) are incorporated as autonomous components hermetically encapsulated in a common module housing, in the hollow interior of which a beam splitter and lens coupling optics are arranged, and which has a fiber connection for a common optical fiber. By means of the transmitter, an optical signal is coupled into the connected glass fiber while, at the same time or with a time delay, a different optical signal can be received from the same fiber. The separation of the two signals is done by the beam splitter, which can also contain a WDM (wavelength division multiplexing) filter, in which one specific wavelength can be reflected and another can be let through.
If, in addition to the one channel in each case in each direction, a further channel is to be transmitted at least in one direction, then an external fiber splitter or external WDM filter can be incorporated into the feeding optical fiber, for example in front of the module. Since this constitutes a relatively impracticable solution, German patent application No. 93 114 859.7 proposes a so-called multichannel transceiver module in which, in the common housing of an above-described conventional BIDI module, at least one further optical transmitter and/or optical receiver with associated lens coupling optics, and at least one further beam splitter, are provided. The optical transmitter and/or optical receiver, or the further optical transmitter and/or optical receiver, are in that case implemented in particular in the form of the so-called TO (transistor outline) standard design, such as has also been described, for example, in German patent application No. 93 120 733.6. The use of specific housing designs such as TO or DIL proves to be relatively inflexible in practice, however, since little freedom for changes is provided. In particular, mounting techniques which are common with semiconductors for large numbers could not be used. In addition, the fixing of fiber connections such as pigtails and receptacles is relatively complicated to carry out in individual assembly.
It has already proven advantageous for transmitting and/or receiving components to be constructed in leadframe technique. This is already known per se. German patent publication DE 196 40 255 A1 describes a method for producing an electronic module having a plastic-encapsulated leadframe, in which electronic components are fitted to the not yet separated leadframes and then the populated leadframes are encapsulated in plastic in two phases. In a first injection-molding phase, the connecting webs with which the conductor tracks of the individual leadframes cohere with one another, and the leadframes themselves cohere with one another, are separated without removing material by means of the first injection mold, and then at least one extra part is inserted into a niche in the plastic body produced during the first injection-molding phase, after which the plastic body is finally encapsulated in a second injection-molding phase using a second injection mold.
European published patent application EP 0 924 540 A1 describes various embodiments of an electrooptical module mounted on a leadframe. For example, FIG. 7 discloses a leadframe with side parts which are bent over at right angles and to whose center part a retaining plate and a plug-in socket housing with a transmitting unit and a receiving unit are fitted. In the case of that module, however, the transmitting and receiving units are each assigned to dedicated fiber connections, so that at least two optical fibers always have to be connected for the transmission of information.
The object of the invention is to provide a optoelectronic bidirectional transceiver module which overcomes the above-noted deficiencies and disadvantages of the prior art devices and methods of this kind, and which enables bidirectional optical message and signal transmission on a single optical fiber. A further object of the present invention is to produce such a transmitting and receiving module as a component which can be surface mounted.
With the above and other objects in view there is provided, in accordance with the invention, a transmitting and receiving module for bidirectional optical transmission, comprising:
leadframe formed with light-passage openings, connection sections, and having first and second sides,
an optical transmitter disposed at one of the light-passage openings and fixed on the first side of the leadframe;
an optical receiver disposed at another one of the light-passage openings and fixed on the first side of the leadframe;
a beam deflection receptacle formed with a fiber connection opening for receiving an optical fiber;
a beam splitter and a deflection mirror fixed on the second side of the leadframe; the
the transmitter and the receiver having electrical terminals connected to corresponding the connection sections of the leadframe.
In other words, the transmitting and receiving module according to the invention has at least one optical transmitter, at least one optical receiver, a fiber connection opening for an optical fiber, lens coupling optics and at least one beam splitter arranged intermediately in the free beam path. The module is produced by the transmitter and receiver each being fixed on one side of a leadframe provided with light passage openings, in the vicinity of the light passage openings, a beam deflection receptacle containing the fiber connection opening, the beam splitter and a deflection mirror being fixed on the other side of the leadframe, and the electrical terminals of the transmitter and receiver each being connected to sections of the leadframe which are separated electrically from one another and are led to the outside as terminal pins or terminal areas.
In accordance with an added feature of the invention, the beam splitter is arranged in a free beam path between the fiber connection opening and the optical transmitter or the optical receiver.
In accordance with an additional feature of the invention, the beam deflection receptacle is a housing formed with an inner cavity, having a lateral housing end forming the fiber connection opening, and having a housing wall facing the leadframe formed with openings opposite the light passage openings in the leadframe; and the beam splitter and the deflection mirror are disposed askew in the cavity and each is arranged opposite a respective the transmitter and the receiver on one side of the light passage opening.
In accordance with another feature of the invention, the beam deflection receptacle is a modular device comprised of each the transmitter and receiver being assigned a modular unit and being fixed to the leadframe at a corresponding the light passage opening.
In accordance with a further feature of the invention, one modular unit is formed by a mirror mount containing the deflection mirror, and a further modular unit is formed by a filter-lens-receptacle unit containing the beam splitter.
In accordance with again an added feature of the invention, at least one connecting element interconnects the modular units.
In accordance with again an additional feature of the invention, a transparent submount covers a respective light passage opening and the transmitter and/or receiver is fixed to the submount.
In accordance with again another feature of the invention, a lens is fixed on a side of the submount opposite the transmitter and receiver, respectively.
In accordance with again a further feature of the invention, a lens is disposed in the beam deflection receptacle, in front of the fiber connection opening. The lens is preferably a spherical lens.
In other words, the preferred beam deflection receptacle essentially has the form of a housing with an inner cavity, whose lateral open housing end forms the fiber connection opening and which, in the housing wall that faces the leadframe, has openings which are opposite the light passage openings in the leadframe, the beam splitter or the beam splitters and the deflection mirror being set askew in the cavity, and the transmitters and receivers in each case being arranged opposite one another. The transmitters and/or receivers can each be fixed to a transparent submount that covers the light passage opening in the leadframe. A lens for focussing the beam can be fixed on that side of the submount which faces away from the transmitter or receiver. Additionally or alternatively, for this purpose a lens, in particular a spherical lens, can also be arranged in the beam deflection receptacle, in front of the fiber connection opening, so that the lens coupling optics that have already been mentioned are formed by the lenses fixed to the submounts and/or the lens arranged in the beam deflection receptacle.
In accordance with yet an added feature of the invention, the transmitter and the receiver are embedded in a plastic covering which is preferably optically opaque and is preferably injection-molded.
In accordance with yet an additional feature of the invention, the transmitters and/or the receivers are surrounded by a metallic housing molding, preferably a metallic shielding plate which, if applicable, is embedded in the plastic covering.
In accordance with a concomitant feature of the invention, the beam splitter is a wavelength-selective beam splitter.
In order to make the module capable of being surface mounted, that is to say suitable for SMT (Surface Mounted Technology), it is advantageous to embed the transmitters and receivers in a plastic covering. It is then possible for the end leadframe sections to be bent around this plastic covering in a suitable way and, on the side of the plastic covering facing away from the leadframe, to be shaped out to form larger, bearing mounting faces, with which the entire module can be soldered onto the printed circuit board in the SMT process. The plastic covering is preferably injection-molded in the injection-molding process onto the optoelectronic components mounted on one side of the leadframe. Said plastic covering preferably consists of an optically opaque plastic compound, so that at the same time optical shielding between the transmitters and receivers is achieved. In addition, metallic housing parts can be molded into the plastic covering, surround the transmitter and receiver and form an electrical shield.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an optoelectronic, bidirectional transmitting and receiving module using a leadframe technique, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.